<!DOCTYPE HTML>
<meta charset=utf-8>
<title>Largest Contentful Paint: observe element rendered by MathML</title>
<body>
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>
<script src="resources/largest-contentful-paint-helpers.js"></script>
<style>
mathml {
  font-size: 12px;
}
</style>
<script>
  async_test(function (t) {
    assert_implements(window.LargestContentfulPaint, "LargestContentfulPaint is not implemented");
    let beforeLoad;
    const observer = new PerformanceObserver(
      t.step_func_done(function(entryList) {
        assert_equals(entryList.getEntries().length, 1);
        const entry = entryList.getEntries()[0];
        assert_equals(entry.entryType, 'largest-contentful-paint');
        assert_greater_than_equal(entry.renderTime, beforeRender);
        assert_approx_equals(entry.startTime, entry.renderTime, 0.001,
          'startTime should be equal to renderTime to the precision of 1 millisecond.');
        assert_equals(entry.duration, 0);
        // Some lower bound: height of at least 12 px.
        // Width of at least 100 px.
        assert_greater_than(entry.size, 1200);
        assert_equals(entry.loadTime, 0);
        assert_equals(entry.id, 'mathml');
        assert_equals(entry.url, '');
        assert_equals(entry.element, document.getElementById('mathml'));
      })
    );
    observer.observe({type: 'largest-contentful-paint', buffered: true});
    beforeRender = performance.now();
  }, 'Element rendered by MathML is observable');
</script>
<math display="block">
  <mrow>
    <msup>
      <mi id="mathml">This is important text! :)</mi>
    </msup>
  </mrow>
</math>
</body>
